Background: Migration, a common phenomenon in sub-Saharan Africa (SSA), is linked to an increased risk of acquiring HIV and sexual risk behavior. However, the impact of migration on the risk of acquiring HIV and sexual behaviors amongst non-migrating members of migrant households has not been studied in detail in SSA. Migration can be disruptive and stressful for households and may result in increased HIV risk. Non- migrating persons living in migrant households may be an unidentified high-risk sub-group for HIV in SSA. Aims: The goal is to assess how migration influences the risk of acquiring HIV and sexual risk behaviors of non-migrating members of migrant households in Rakai, Uganda. The study aims to: 1A) Compare sociodemographic and household family structure among in-migrating, out-migrating and non-migrating households; 1B) Compare HIV prevalence, prevalence of sexual risk behaviors, viral load suppression between non-migrating members of in- and out-migrant households with members of non-migrant households; 2) Assess incidence of HIV, and changes in sexual risk behavior of non-migrating household members following the in- or out-migration of a household member; and 3) Qualitatively explore the impact of out- migration amongst couples on non-migrating partners? HIV and sexual behavior perceptions and practices. Approach: This study will use existing data for Aims 1 and 2 from the Rakai Community Cohort Study (RCCS), an open population-based cohort of approximately 22,000 people aged 15-49 years across 40 communities, collected between 2011 and 2017. Aim 1 will use random intercept Poisson regressions with robust standard errors to assess the prevalence of sexual risk behaviors, viral suppression , and HIV comparing migrant and non-migrant households. Aim 2 will use random intercept Poisson regressions with robust standard errors to determine if in or out-migration events within households are associated with changes in sexual risk behaviors or risk of HIV acquisition. In Aim 3, we will conduct in-depth interviews with RCCS members who reported that their partners had migrated recently. The study will characterize the effect of migration on non-migrating members by (i) detecting differences in HIV prevalence and behavior using cross- sectional data; (ii) assessing the marginal effect of in- and out-migration events on changes in sexual behavior and incident HIV infection; and (iii) exploring how migration may impact sexual risk behavior, risk of HIV acquisition, and care-seeking behavior if HIV+, for couples with migrant spouses. Training: The proposed study will serve as the doctoral dissertation for Ms. Young, a doctoral student at Johns Hopkins Bloomberg School of Public Health. Her mentorship team have extensive experience in Rakai, Uganda and complementary technical skills. The training plan combines coursework, field research, and mentorship. The proposed study aligns with research priorities aiming to understand the social and behavioral factors influencing HIV risk, and linkage to and retention in HIV care.